Research Articles

Abstract:
Measurement of microelectromechanical systems (MEMS) geometry is
critical for device design and simulation, for material property
extraction, and for post-fabrication trimming. In this paper,
electrostatically-driven laterally resonant comb-drive test
structures with prescribed changes in spring width are used to
ascertain systematic variations in process offsets (edge biases)
and sidewall angles. The technique is both in-situ and non-destructive.
An analytical model for the resonant frequency, tuned with
three-dimensional (3D) simulations using MEMCAD, includes effects
of a distributed mass, residual stress, and compliant supports.

Abstract:
The squeezed-film damping component of the pull-in time of an
electrostatically-actuated micromechanical fixed-fixed beam is
shown to be a sensitive, and nearly linear function of ambient
air pressure in the measured range of 0.1 mbar to 1013 mbar (1 atm
or 760 Torr). The data and simulations show that pull-in type
devices will enable MEMS sensors for broad-range absolute pressure
measurements, and for in-situ leak monitoring of hermetically
sealed packages containing other sensors or IC´s. The sensors
are compatible with any MEMS fabrication processes that allow
out-of-plane electrostatic actuation, including surface micromachining
and silicon wafer-bonding, and they do not require a cavity sealed
at vacuum or at a reference air pressure.